Speed stabilizing device for sound record films



Aug. 6, 1940.

0. K. KOLB Filed May 25, 1959 Fig. 1.

Inventor; 0 66- by Attorney t uzi ml T 2.210372 UNITED STATES PATENT;OFFICE 1 srannis'rammzmo' DEVICE FOR SOUND I a EG W S Otto'Kurt Kolb,chiswick liondon, Eng imamsigner to British Acoustic im filed,"

,London, England, a British-company I Application May 25.1939. SerialNee-15,676

I 1 in Great Britain June-13, 8

This invention relates to devices'tti or use in rigidly attached to thedrum. shaft which-is film feeding mechanisms for the purpose o irenkpower-driven through an elastic coupling, the dering the speed of filmfeed as constantas p'os said box containing the heavy; flywheel sible atthe point at which sound recording is which is carried round by fluidfriction, but effected, or at which sound reproduction by there. aredifilculti'es in constructing such a de- 5 photo-electric meanstakesplace. vice in a simple and effective form. The inner;

It has long been known that if a film on which flywheel is relativelyheavy and must be accua sound record is to ,be made or from-which arately balanced while being carried unreliable soundrecord is to-berep'roducedis taken round antiefriction bearings within the hollowshell, a drum so as to embrace an appreciable arc or and the'clearancesmust be correctly adjusted 10 the periphery of this, and if the film isdriven to provide the necessary degree of couplingbeby suitable means sothat in turn it drives the tween shell and flywheel. Yet again, inconnec drum in the manner of a belt, and if associated. tion withthe'shafts of high speed engines and with-the drum mechanically there isa flywheel, the like in which many of the present problems the eflect"of this system is' to add inertia to the do not arise, it has beenproposed to fix a hollow 16 film (which in itself is virtually withoutmass) drumtothe shaftand to use liquid in'the drum to and thisarrangement serves to maintain the damp torsional vibrations andtoincrease the film .velocity at the recording or reproducin internalsurface by the provision of inwardlypoint, substantially constant.projecting fixed gills or vanes.

i 20 The film is generally deflected out of a straight According to thepresent invention, a flywheel m path on one or both sides of its pointof conhaving acomparatively light hollow shell or tact with the drum byelastic means either incontainer is carried by the shaft of the filmdruin herent inthe film itself or separately applied which is drivensolely by the film itself, the shell thereto, whereby vibratory speedchanges imhaving no internal bearings or loose parts,-but

8b parted to the film by or through the driving v containing a liquid ofhigh viscosity which pro- 5' mechanism are not applied to the drum orare .vides the necessary damping effect. In such an reduced inintensity-so that the inertia of the arrangement, the viscous liquidabsorbs energy drum system prevents speed changes being presto varyingdegrees throughout its mass with ent in the portion of a film passingthe sound changes of velocity, and pick-up of the flywheel '80reproducing or recording point. If the system, mass is gradual instarting as ls-desirable for .comprising thefiywheel; film-driven drumand avoiding excessive. film stresses. The liquid -film form amechanical oscillatory-system, speed should 'be of high density so as tokeep. the size fluctuations known ashunting can .be set up, of thecasing as small as possible. The'casing and will seriously interferewith the recording *can be light and indeed it may be of material 88'and reproduction of the sounds, but by the use' 10W p fi gravitykfli hasonly act as of suitable damping 'means applied eitherto the Conta andfor transmitting the q e 0 flywheel system or to the-elastic meansreferred and from the liquid. The damping'in the liquidto such huntingeffects and consequent fiuctuais very efifective and makes it possibleto use less tions in the film speed can be largely eliminated. totalmass for the fl wheel, so that t e compli- 40 Any-system having asubstantial flywheel mass ance of thefilm acting through the curved por-4o rigidly attached to the drum over which th fil tions is increased,andthe efilciency of the system passes has the further disadvantage thatin as a filter for eliminating transient disturbances starting upquickly, the film is subjected to conis improved. siderable tension inaccelerating the flywheel up It is ou d a e Stabilizing effect o fiY-'to its normal speed and this leads to film breakwheel constructedaccording to the invention, 45

ages. V becomes more considerable as the total mass of Various proposalshave been made for overthe flywheel syste t n limits, redllced acomingthe difllculties mentioned above. In f l t0 the moment O inertia} 6f t eViscous some cases, it was suggested to divide the fiyliquid anddampingfactol 1 the v sc s ty wheel massinto two parts coupled by fluidfric- Of that q d- With p i m l e- 50' tion or by electromagnetic drag,and this may .tween these factors; the compliance of the film providethe required damping but still leaves the acting thro h the ved portionsor loops is film subject to considerable starting loads. increased owingto the reduction of the tension Other proposals which overcome thislatter difii-, of the film necessary for driving 1 the flywheel '65culty involve the-useof a thin-walled hollow box and maintaining itinsteady i'irmtion. Cruise'- quently, the effectiveness of the flywheelsystem as a mechanical filter in eliminating transient disturbances, isimproved.

As no internal mechanical hearings or loose parts requiring accurateclearances are provided, the construction is substantially simplified.

In order that the invention may be clearly understood and readilycarried into efiect, one form .of construction in accordance therewithwill now be described merely by way of example, with reference to theaccompanying drawing,,in which:

form of flywheel die and drum; and 3 Figure 2 is a side elevation of theflywheel with its drum and the associated parts.

Figure l is a czfitral sectional elevation of one th the associateddriving spin- The shell or container of the flywheel is a" drum. [2 overwhich the sound record film passes,

and by means of which alone, the whole flywheel system can be spun orrotated. The spindle l l is carried on the practically frictionless ballbearings l3 and I4. Two filling holesare formed in small bosses I5, I 6secured in the flat wall of the dished piece 2, a liquid-tight jointbeing made in each case, for example by riveting. The holes are closedby two screwed plugs ll, l8.

It is intended that the shell or container 2, 3 shall be filled with aviscous liquid, which may be glycerine or a mixture of glycerine andwater or other solvent, or it may be a thick oil such as castor oil, ora viscous solution such as sugar syrup, cellulose esters or ethers insolvents, and so forth. The specific gravity of glycerine is 1.26 andits viscosity is about 8.5 poises at 20 C. .The viscosity of castor oilis suflicient for the purpose, but its density is a little belowunity sothat a larger bulk of castor oil is needed for the flywheel action. Asthe efliciency of the damping action depends on the viscosity, it isdesirable to use a liquid which has a; viscosity of the order of say '5poises at the working temperature, say 20 C. and the greater the densityof the liquid the better for the purpose in view. In some forms of theapparatus, in order to-increase the damping, an additional partition orseptum 6 may be provided lying ina plane of rotation and secured.

to the rim at the joint 4, and, indeed, more than one such partition maybe provided.

The partition is perforated at l to allow of circulationofthe viscousliquid and to allow the shell to be easily filled, but instead, theremay be a central aperture in it around the hub or boss 8. Instead ofbeing fixed to the outer shell, the partition 6 may be carried by thecentral hub or boss 8 in which case, a circular space is left betweenthe outer edge of the partition 6 and the casing l.

As seen in Figure 2 the driving drum I2 is provided with afreely-turning pressure or lay-on roller l9 and around it, the film 20passes. A feed sprocket 2| carries the film towards the drum l2 and thefilm 20 is drawn at substantially constant speed over and around saiddrum by the sprocket 22. Owing to the very small tractive force requiredto maintain the drum and flywheel in motion, well defined loops 23 and24 form in the film 20 which having great elasticcompliance inconjunction with the inertia and damping of the flywheel system servesvery completely to eliminate velocity variations in the travel of thefilm 20 at the recording or reproducing point.

It is obvious that various small modifications may be made in theconstruction; for example, although it is not of importance if thecasing is slightly distorted by centrifugal forces, the pieces 2, 3 maybe stiffened or rendered more rigid,'for example, by radial ribsattached to the inside or outside of the flat faces of the pieces 2, 3or bymeans of circular corrugations.

Iclaim: 1

1. In a feeding mechanism for sound record films, the combination of adrum around which the film passes and driven solely by the film itself,a speed-stabilizing flywheel in driving relationship with said drum andcomprising a container and a viscous liquid within said containerconstituting substantially the whole of the flywheel mass.

2. In a feeding mechanism for sound record films, the combination of ashaft, a drum secured to said shaft around which drum the film passesand which is driven solely by the film itself, a speed-stabilizingflywheel also secured to said shaft and comprising a container and aviscous liquid within said container constituting substantially thewhole of the flywheel mass.

3. In a feeding mechanism for sound record films, the combination of adrum around which the film passes and driven solely by the film itself,a speed-stabilizing flywheel in driving relationship with said drum andcomprising a light thin-walled container and a viscous liquid withinsaid container constituting substantially the "films, the combination ofa shaft, a drum secured to said shaft around which drum the film passesand which is driven solely by the film itself, a speed-stabilizingflywheel also securedto said shaft and comprising a container ofmaterial of low specific gravity, and a viscous liquid within saidcontainer constituting substantially the whole of the flywheel mass.

6. In a feeding mechanism for sound record films, the combination of ashaft, a drum secured to said shaft around which drum the film passesand which is driven solely by the film itself, a speed-stabilizingflywheel also secured to said shaft and comprising a container and aliquid within said container, said liquid having a high viscosityexceeding 5 poises constituting substantially the whole of the flywheelmass.

7. In a feeding mechansm' for sound record films, the combination of adrum around which the film passes, means for positively forwarding thefilm whereby said drum'is solely driven by the pull of the fihn itself,a speed-stabilizing flywheel in driving relationship with said drum andin said container constituting substantially the whole of the flywheelmass.

8. In a feeding mechanism for sound record films, the combination of adrum around which the film passes, means for positively forwarding thefilm whereby said drum is solely driven by the pull of the film itself,a speed-stabilizing flywheel in driving relationship, with said drum andcomprising a container, at least one partition located internally ofsaid container and fixed to the wall thereof and a viscous liquid withinsaid container and in contact with said partition constitutingsubstantially the whole of the f ywheel mass.

9. In a feeding mechanism for sound record films, the combination of ashaft, a drum secured to said shaft and around which the film passes,means for positively forwarding the film whereby said drum is solelydriven by the pull of the film, a speed-stabilizing flywheel 'alsosecured to said shaft andcomprising a light thin-walled cylindricalcontainer, at least one partition located internally of said containerin a plane transverse to the axis thereof and fixed to said container torotate therewith and a viscous liquid within said container and incontact with said partition constituting substantially the whole of theflywheel mass.

10. In a feeding mechanism for sound record films, the combination of ashaft, a drum secured to said shaft and around which the film passes,means for positively forwarding the filml whereby said drum is solelydriven by the pull of the film, means for forming the film into twoloops, one of said loops preceding and the other following the passageof the film over said drum, a speedstabilizing flywheel indrivingrelatio'nship with said drum and comprising a container and aviscous liquid within said container constituting substantially thewhole of the flywheel mass.

11. In a feeding mechanism for sound record films, the combination of ashaft, a drumsecured to said shaft around which drum the film passes andwhich is driven solely by the film itself, a speed-stabilizing flywheelalso secured to said shaft and comprising a container and a viscousliquid within said container, said liquid having a density high incomparison with that of water constituting substantially the whole ofthe flywheel mass.

- O'I'IO KURT KOLB.

